Protein Kinase LTRPK1 Influences Cold Adaptation and Microtubule Stability in Rice

Rice LTRPK1, which encodes a member of the casein kinase I family, has been reported to be involved in root development, hormone response, and metabolic processes. Here we further show that LTRPK1 participates in stress resistance by regulating cytoskeleton rearrangement and formation of cold tolerance and adaptation. Semiquantitative RT-PCR analysis revealed enhanced expression of LTRPK1 in plants subject to low-temperature stress at 4 °C, suggesting a role in low-temperature-related cell responses and signal transduction pathways. Further analysis of LTRPK1-deficient transgenic plants showed that under low-temperature treatment, the growth rate of transgenic plant primary roots, which is commonly used as an indicator for cold stress response abilities, was less inhibited than that of control plants. Moreover, damage to the plasma membrane of root cells in LTRPK1-deficient plants was greater than that of controls as measured by relative electrical conductivity (REC). The malondialdehyde (MDA) content of LTRPK1-deficient plants also increased over that of the control, indicating increased plasma membrane permeability. Further immunofluorescence localization observations indicated that microtubules of transgenic plants subject to low temperature disassembled more rapidly, whereas the control plant microtubules in most cells of the root elongation zone kept their normal habitus, which suggested that LTRPK1-deficient plants had reduced capacity to resist low-temperature stress through regulation of microtubule assembly. These results demonstrate involvement of LTRPK1 in low-temperature stress and provide new insight for rice breeding and germplasm innovation to improve crop cold tolerance.     

Cutting edge: profile of chemokine receptor expression on human plasma cells accounts for their efficient recruitment to target tissues

We systematically examined the repertoire of chemokine receptors expressed by human plasma cells. Fresh bone marrow plasma cells and myeloma cells consistently expressed CXCR4, CXCR6, CCR10, and CCR3. Accordingly, plasma cells responded to their respective ligands in chemotaxis and very late Ag-4-dependent cell adhesion to fibronectin. Immobilized CXC chemokine ligand (CXCL)16, a novel transmembrane-type chemokine and CXCR6 ligand, also directly induced adhesion of plasma cells without requiring G(alpha i) signaling or divalent cations. Furthermore, we revealed consistent expression of CXCL12 (CXCR4 ligand), CXCL16 (CXCR6 ligand), and CC chemokine ligand 28 (CCR10 and CCR3 ligand) in tissues enriched with plasma cells including bone marrow, and constitutive expression of CXCL12, CXCL16, and CC chemokine ligand 28 by cultured human bone marrow stromal cells. Collectively, plasma cells are likely to be recruited to bone marrow and other target tissues via CXCR4, CXCR6, CCR10, and CCR3. CXCR6 may also contribute to tissue localization of plasma cells through its direct binding to membrane-anchored CXCL16.     

The Caenorhabditis elegans Elongator Complex Regulates Neuronal α-tubulin Acetylation

Although acetylated α-tubulin is known to be a marker of stable microtubules in neurons, precise factors that regulate α-tubulin acetylation are, to date, largely unknown. Therefore, a genetic screen was employed in the nematode Caenorhabditis elegans that identified the Elongator complex as a possible regulator of α-tubulin acetylation. Detailed characterization of mutant animals revealed that the acetyltransferase activity of the Elongator is indeed required for correct acetylation of microtubules and for neuronal development. Moreover, the velocity of vesicles on microtubules was affected by mutations in Elongator. Elongator mutants also displayed defects in neurotransmitter levels. Furthermore, acetylation of α-tubulin was shown to act as a novel signal for the fine-tuning of microtubules dynamics by modulating α-tubulin turnover, which in turn affected neuronal shape. Given that mutations in the acetyltransferase subunit of the Elongator (Elp3) and in a scaffold subunit (Elp1) have previously been linked to human neurodegenerative diseases, namely Amyotrophic Lateral Sclerosis and Familial Dysautonomia respectively highlights the importance of this work and offers new insights to understand their etiology.     

Removal of persistent organic pollutants from micro-polluted drinking water by triolein embedded absorbent

A new biomimetic absorbent, cellulose acetate (CA) embedded with triolein (CA-triolein), was prepared and applied for the removal of persistent organic pollutants (POPs) from micro-polluted aqueous solution. The comparison of CA-triolein, CA and granular activated carbon (GAC) for dieldrin removal was investigated. Results showed that CA-triolein absorbent gave a lowest residual concentration after 24 h although GAC had high removal rate in the first 4 h adsorption. Then the removal efficiency of mixed POPs (e.g. aldrin, dieldrin, endrin and heptachlor epoxide), absorption isotherm, absorbent regeneration and initial column experiments of CA-triolein were studied in detail. The linear absorption isotherm and the independent absorption in binary isotherm indicated that the selected POPs are mainly absorbed onto CA-triolein absorbent by a partition mechanism. The absorption constant, K, was closely related to the hydrophobic property of the compound. Thermodynamic calculations showed that the absorption was spontaneous, with a high affinity and the absorption was an endothermic reaction. Rinsing with hexane the CA-triolein absorbent can be regenerated after absorption of POPs. No significant decrease in the dieldrin removal efficiency was observed even when the absorption–regeneration process was repeated for five times. The results of initial column experiments showed that the CA-triolein absorbent did not reach the breakthrough point at a breakthrough empty-bed volume (BV) of 3200 when the influent concentration was 1–1.5 μg/L and the empty-bed contact time (EBCT) was 20 min.     

椴树阔叶红松林群落主要树种径级结构研究

椴树阔叶红松林群落主要树种径级结构研究孙伟中代力民章一平（中国科学院沈阳应用生态研究所,１１００１５）ＳｔｕｄｙｏｆＤｉａｍｅｔｅｒＢｒｅａｓｔＨｉｇｈＳｔｒｕｃｔｕｒｅｏｆｔｈｅＭａｉｎＴｒｅｅｓｉｎＴｉｌｉａＢｒｏａｄｌｅａｖｅｄＫｏｒｅａｎＰ...     

Sclerite calcification and reef-building in the fleshy octocoral genus Sinularia (Octocorallia: Alcyonacea)

Alcyonacean octocorals in tropical reefs are usually not considered as reef builders. Some Sinularia species, however, are capable of consolidating sclerites at the colony base to form spiculite. Nanwan Bay, southern Taiwan, features both fossilized and recently formed boulders composed of spiculite, thus demonstrating the role of Sinularia in contributing to the reef structure. Section radiography of an 18.5 kg spiculite boulder demonstrated a regular density banding of 3–6-mm intervals. Core survey indicated spiculite coverage of 25–30% on the live reef and of 30–40% on the uplifted boulders. Cores taken from living Sinularia revealed a distinct transition from discrete sclerites to compact spiculite and amorphous calcium carbonate cementing the sclerites. In the widespread S. gibberosa, sclerite formation appeared to start intracellularly, followed by a prolonged extracellular calcification process. At the calcification site, multiple sclerocytes formed expanded pseudopod-like membranes that interconnected, forming multicellular vesicles (MCVs) around the sclerites. The MCVs and the pseudopods disappeared at sclerite maturation, followed by degradation of the sclerocytes around the mature sclerites. At the colony base, granular vesicles were distributed among the sclerites, indicating a cementing process in progress. These findings suggest that colonies of Sinularia are able to cement sclerites and consolidate them at their base into spiculite, thus making them reef builders.     

Cloning and characterization of an mRNA encoding a novel G protein alpha-subunit abundant in mantle and gill of pearl oyster Pinctada fucata

Nacre formation is an ideal model to study biomineralization processes. Although much has been done about biomineralization mechanism of nacre, little is known as to how cellular signaling regulates this process. We are interested in whether G protein signaling plays a role in mineralization. Degenerate primers against conserved amino acid regions of G proteins were employed to amplify cDNA from the pearl oyster Pinctada fucata. As a result, the cDNA encoding a novel G(s)alpha (pfG(s)alpha) from the pearl oyster was isolated. The G(s)alpha cDNA encodes a polypeptide of 377 amino acid residues, which shares high similarity to the octopus (Octopus vulgaris) G(s)alpha. The well-conserved A, C, G (switch I), switch II functional domains and the carboxyl terminus that is a critical site for interaction with receptors are completely identical to those from other mollusks. However, pfG(s)alpha has a unique amino acid sequence, which encodes switch III and interaction sites of adenylyl cyclase respectively. In situ hybridization and Northern blotting analysis revealed that the oyster G(s)alpha mRNA is widely expressed in a variety of tissues, with highest levels in the outer fold of mantle and epithelia of gill, the regions essential for biomineralization. We also show that overexpression of the pfG(s)alpha in mammalian MC3T3-E1 cells resulted in increased cAMP levels. Mutant pfG(s)alpha that has impaired CTX substrate diminished its ability to induce cAMP production. Furthermore, the alkaline phosphatase (ALP) activity, an indicator for mineralization, is induced by the G(s)alpha in MC3T3-E1 cells. These results indicated that G(s)alpha may be involved in regulation of physiological function, particularly in biological biomineralization.     

Ala99ser mutation in RIα Regulatory Subunit of protein kinase A causes reduced kinase activation by cAMP and arrest of hormone-dependent breast cancer cell growth

Expression of the RI regulatory subunit of protein kinase A type I is increased in human cancer cell lines, in primary tumors, in cells after transformation, and in cells upon stimulation of growth. Ala99 (the pseudophosphorylation site) of human RI was replaced with Ser (RI-p) for the structure-function analysis of RI. MCF-7 hormone- dependent breast cancer cells were transfected with an expression vector for the wild-type RI or mutant RI-p. Overexpression of RI-P resulted in suppression of protein kinase A type II, the isozyme of type I kinase, production of kinase exhibiting reduced cAMP activation, and inhibition of cell growth showing an increase in G0/G1 phase of the cell cycle and apoptosis. The wild-type RI overexpression had no effect on protein kinase A isozyme distribution or cell growth. Overexpression of protein kinase A type II regulatory subunit, RII, suppressed RI and protein kinase A type I and inhibited cell growth. These results show that the growth of hormone-dependent breast cancer cells is dependent on the functional protein kinase A type I.     

观赏植物花期调控途径及其分子机制

开花期控制对观赏植物的生产和应用具有重要意义。目前关于高等植物成花机理的研究已经取得了突破性进展,为观赏植物花期调控开辟了新途径。该文总结了观赏植物花期调控的途径和方法,并对改良观赏植物花期的技术思路做了初步分析。通过与高等植物成花机制研究的对比分析发现,观赏植物开花机理的研究已有了长足发展,一些观赏植物的转基因研究也取得了丰硕成果。利用分子设计育种途径改良观赏植物的开花期,突破了传统方法的局限性,其研究和应用前景非常广阔。